Diffusion barriers are commonly employed in semiconductor wafer fabrication to restrict diffusion between materials, such as preventing diffusion of dopant from one material to another. Diffusion barrier layer materials can be conductive or insulative. Titanium nitride and titanium are example diffusion barrier materials which are conductive. Such materials can be used, for example, at the base of a contact over or to a diffusion region in a semiconductive substrate, and be positioned intermediate the diffusion region and an overlying conductive layer.
Diffusion barriers can also be crystalline or amorphous. When comprised of a crystalline material, grain boundaries of the crystals which extend all through the layer adversely impact the material's diffusion barrier properties. This is due to potential pathways for diffusion of material along the grain boundaries being created from one surface of the layer to another. It would be desirable to develop methods and constructions which produce better barrier layer materials or constructions which are less susceptible to material diffusion along grain boundaries.